Academic OB/GYN Podcast Episode 32 – Journals for February and March 2011

Paul Browne and I discuss two companies that did some foolish things (KV and Sequenom), the link between terbuataline and autism (not so much), how nulliparous inductions don’t increase cesareans (if you make a bad enough study), and a few other odds and ends.

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When I was induced at 41w3days (with a LOW bishops score — 0 dilation, barely effaced, and a -3 station, but no other reason for the induction other than being post-dates), my doctor told me that inductions at 41 weeks do not increase the likelihood of a c-section compared to women that go into labor spontaneously at 41 weeks. I had a c-section at 41w6days. I guess I’m kind of wondering if the study my doctor referenced was similarly flawed as the one you make fun of here. What do studies say about non-elective inductions at 41, 42 weeks versus waiting it out and going into labor spontaneously?

There are some nice prospective randomized studies comparing expectant management at 41 weeks to induction, and they do not show an increase in cesarean rate with induction. These studies are properly done and generally without bias, as opposed to the retrospective cohort design of the study we mention on the podcast, which is overwhelmed with selection bias (a connection between which group the patient is in and the measured outcome, other than by the specific issue under study).

Induction at 41 weeks is pretty standard and is evidence based enough to go with. There is nothing wrong, however, with waiting until 42+ weeks if one does fetal monitoring and measurement of amniotic fluid, which probably will catch most of the rare fetal demises that will occur between 41 and 42 weeks.

Thank you for your thoughtful response! As an aside, I probably shouldn’t have said there was no other reason to induce — at my final appointment I had a dwindling AFI so I don’t think waiting much longer would have been appropriate.

Low AFI at term is another soft indication for induction. Studies of induction vs expectant for isolated oligo have not shown a benefit to induction in terms of neonatal outcomes, but at 41 weeks its certainly pushes one towards delivery. The difficult cases are the 39 weekers with an AFI of 4. Most MFMs would say induce, but I don’t think the evidence supports that action.

“Induction at 41 weeks is pretty standard and is evidence based enough to go with. There is nothing wrong, however, with waiting until 42+ weeks if one does fetal monitoring and measurement of amniotic fluid, which probably will catch most of the rare fetal demises that will occur between 41 and 42 weeks.”
How reassuring to hear this, Nicholas. Thank you.

Since Shane Marsh posted something, I do have another question. (I realize that it’s not your job to answer random questions, but I am curious and I don’t feel as it’s something I could call my OB for or schedule an appointment to discuss.) I also posted this on the Skeptical OB, but no one really responded. Here it is: I was told that only 55% of women with my Bishops score at 41 weeks (which was nada) deliver vaginally. Is this statistic calculated with or without a cervical ripening agent? After 3 rounds of cytotec and a foley bulb, I was able to get to about 3 ish centimeters. Does this really mean that only 55% of women showing up for an induction with a closed cervix will deliver vaginally?

Cervical ripening agents do not seem to affect the rate of cesarean delivery, only the mean time from start of induction to delivery. The upshot of this (downshot really) is that an unfavorable cervix is associated with a high rate of induction failure, irrespective of cervical ripening agent use.

For a nulliparous woman with a bishop score of < 4, the cesarean rate is about 50%. Multiparas have much more success with unfavorable inductions.

If a woman is 41 weeks with an unfavorable cervix, however, the data suggests that she is not likely to become substantially more favorable over the next few weeks. A randomized trial of induction vs expectant management at 41 weeks did not find any difference in cesarean rates between the two groups. The induction group did have more cesareans for arrest, but this was balanced by a greater number of cesareans for bad fetal strips in the expectant group, likely because of decreased placental oxygen transfer in the later term placentas.

I’ve read that – that study is biased, though.. Jessica.. The doctors knew the women were 41 weeks… And today, 41 weeks = riskier.. ooh placentas die (more often after 41 weeks? pause. No?) in docs minds.. even though it doesn’t “seem to increase the risk of cesarean section”, is that really saying anything bad or good (since the cesarean section rate is inflated anyway,, could they not. inflate it further with their biases?) ?! Comparing a group of women who are being induced .. to women who are not.. at a gestation that the docs believe is riskier? Would it not be more scientific to blind it maybe just a little bit?!

I mean the nurse midwives at the practice I was at were practically panting when I said no to induction at 41 weeks, and then this female obstetrician actually said “after 41 weeks the baby will shrink” (?!?! this was because at an ultrasound at 41 and 1, they had estimated baby to be 8 lbs.. the next ultrasound 4 days later estimated 7 lbs… this was why she said that LOL) despite a reassuring BPP and NST.. and honestly.. he was not shrinking it was just .. ultrasounds are not that reliable for weight.

lol, baby’s shrink after 41 weeks. didn’tcha know?!? He was 7 lbs a couple days later. Vaginally. No induction..

At the doctor…. Really, weak placentas ? Do you have evidence for the placentas being “aged and weak” and decrepid particularly after 41 weeks vs earlier or later or is this just personal speculation? Haven’t you seen “aged” unhealthy placentas earlier on.. particularly with babies that have true IUGR? If so, what’s your explanation for that? They aged prematurely? Or more likely.. they were compromised in some manner from the start?! If it’s just personal speculation, which I suspect, maybe you could keep that sort of crap to yourself? Also, what makes you believe that the more frequent bad fetal strips weren’t caused by something they did to the “expectant management” group vs. said dying placentas or anything else (like, orange gas that all of the patients happened to be allergic to being emitted into the room!.. weird.. but.. relevant since the study was so crap controlled)? They waited for them to go into labor on their own. What they did after that, we do not know. Pit? Epidurals? Make them stand on their head and sing aaahhhh? Said allergenic orange gas? Do you know?! If not, then what makes you certain about anything?

I don’t trust them, myself (the MDs). Not on this topic in particular.

They get all weird about post-dates and post-term. They never consider it might also be them doing something wrong. It’s always placentas or shrinking babies and whatnot. I say. Drink lots of water before ultrasounds.. Don’t want another pretend low AFI…

1. Placentas do progressively lose oxygen and nutrient transferring ability as they age. This is the primary reason for post dates related loss. One only need to deliver hundreds of babies at various gestational ages and this is quite clear. Particularly ‘old’ placentas have calcium deposits throughout (grade 3 placentas).

2. I agree there is nothing wrong with going past 41 as long as one does some monitoring, which likely reduces if not eliminates the additional risk of stillbirth.

3. You’re right, babies don’t shrink.

4. Your comments on the study are interesting to a point… These studies have been done several times, and have confirmed that induction at 41 weeks does not seem to increase cesarean rate. They do show an interesting finding, which is that women managed expectantly do have a lower rate of cesarean for arrest, but that is replaced by an increased rate of cesarean for non-reassuring fetal status (fetal distress in labor), suggesting that what one gains by avoiding induction is lost through loss of placental function over.

I would not call these studies biased at all. They are done exactly right. The problem you’re having is that you want to somehow compare obstetrician care to some other kind of care (midwifery?), which just isn’t what those studies did. Your comments about blinding make no sense. Please design me a study that will answer this question in a ‘less biased’ way and let me know.

5. Your fourth paragraph is troubling to me. You are here espousing a medical opinion that someone might theoretically read and follow, but that is just made up of nonsense. The fact that you do not understand placental physiology does not invalidate the decades (maybe even centuries) of research of which you are unaware.

There are many reasons for a fetus to be growth restricted. One of them is so called uteroplacental insufficiency. The placenta in this case is restricted in its ability to pass nutrients and oxygen, but on a pathological level does not have the same defect as a post-dates ‘old’ placenta.

>> I don’t trust them, myself (the MDs).

Right – and it appears to me that your points come not from an understanding of the science underlying these issues, but rather from your lack of trust of physicians in general.